---
slug: /guides/output
title: Build Output
---

This list gives you some tips to control and manage the generated files coming
out of the `build_runner`.

## Use the correct SDK version

The version of the `sdk` used in the `pubspec.yaml` has a big influence on what
packages are downloaded as part of the `pub get` command. Make sure you are
using at least **`2.12.0`**.

## Continuous generation with the `watch` command

As you work on your stores, you would want to keep the `build_runner` active,
constantly generating the `*.g.dart` files. The trick to keep it running is to
use the **`watch`** sub-command, as shown below:

```
flutter pub run build_runner watch
```

OR

```
pub run build_runner watch
```

## Starting a clean build

Sometimes `build_runner` will simply refuse to run the build if you already have
some generated files. This could happen if the version of **dart** or
**flutter** has changed. In those case, it is best to start clean and regenerate
all the files. You can either use the `clean` sub-command or simply start off by
deleting the existing generated files.

- Clean and remove all generated files

```
flutter pub run build_runner clean
```

- Delete conflicting files

```
flutter pub run build_runner watch --delete-conflicting-outputs
```

## Unable to run the app in iOS Simulator (Old iOS Deployment Target)

It is possible that sometimes your app would simply fail to run on the
simulator. You might see a weird error message like so:

```
info flutter.tools [ +206 ms] An error was encountered processing the command (domain=NSPOSIXErrorDomain, code=22):
info flutter.tools            Failed to install the requested application
info flutter.tools            The application's Info.plist does not contain CFBundleVersion.
info flutter.tools            Ensure your bundle contains a CFBundleVersion with a valid semantic version number.
```

The real issue seems to be the fact that the `Deployment Target` has been set to
**iOS 8.0**. This should be at least **12.0**. Open up the `Runner.xcworkspace`
file in **XCode** and change the deployment target as below:

import deploymentTarget from './deployment-target.png';

<img src={deploymentTarget} width={'100%'} />

- Once you make this change, be sure to _**remove the app**_ from your simulator
  and _**restart the simulator**_.
- With that change, you should be back in action!
